Piston of engines, compressors, motors, and other machines having reciprocating pistons.



H. J UN KERS.

PISTON or ENGINES, commmssoas, MOTORS, AND OTHER. MACHINES HAVING REOIPROGATING PISTONS. APPLICATION FILED NOV. 30, 1912.

1,102,590, 7 Patented July 7,1914.

UNITED STATES. PATENT OFFICE...

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PISTON OF ENGINES, GOMPRESSOBS,I MOTORS, MACHINES HAVING IR'IEGIIPROCA'JPIILN'G-v PISTONS.

Specification of Letters ratent. Patented July '7, 1914.

To all whom it may concern: Be it known that I, HUGO JUNKERS, a

subject of the King of Prussia, residing at- No. 68 Bismarckstrasse, Aix-la-Chapelle in the Kingdom-of Prussia, Empire of ermany, have invented certain new and useful Improvements; in and Relating to the P1S-' ing reciprocating pistons in which the pistons are subject to a high-degree of heat on one endthereof in addition to great me-- chanical stress, such, for instance, asgas and oil engines, compressors, and the like. In such machines it 'is desirable that the heat be distributed or conducted away as quickly as possible in order to guard against distortion and breakage of the piston asmuch as possible. Various means have heretofore been employed to this end, such, for instance, as the provision of heat radiating ribs, the provision of a water circulation to and from the piston, andconducting heat from the piston to the cylinder wall which latter is cooled by air or water. The cooling of the piston 1 by conducting cooling water to and from the same involves considerable difficulty both in the construction of the machine and in its operation, as such water must be conveyed to and from a pis ton which is reciprocating with considerable velocity and, furthermore, the reciprocating movement given to the cooling waterin the piston interferes with the continuous flow of. the water in the same direction. The

cooling of the piston merely by the provi-g heat from metal to the surrounding air due merely to contact of the air with the metal,

'is-relatively slow. The same is true ofthe transfer of heat from a piston to the walls of the inclosing cylinder, particularly with respect to the centralportionof theliead of the piston. This invention is directed to the provision of improved means for cooling a. piston involvmg the distribution of heat which is produced at one point on or over one wall of the piston to the whole of the piston, so that stresses concentrated .over a substantially small portion of the piston are avoided. With the. constructions heretofore employed, heat developed at-the center of the operative face of the piston has been conductcdtothe cylindrical wall merely by the metal of the cylinder itself so that suchheat has been transmitted a substantial distance through metal of comparatively small cross-sectionin order to reach the points of lower temperature. In accordance with this invention, however, the piston is made hollow and a liquid is provided within the cavity in the piston completely 'inclosed within the piston; this liquid transfers heat directly from the operative face of the piston to the cylindrical wall and other parts which are of relatively low temperature and vwhich are in contact with the cooler portions of the cylinder itself. To increase the effect of this liquid inclosed within the hollow piston, I provide means for causing a circulation of'the cooling water whereby a more rapid and'thorough distribution of theheat is effected. For this purpose, ribs may be may be provided within the piston which are caused to move to and fro therein by the reciprocating movement of the piston. Such bodies moving within the piston, serve to effect circulation of the water and eyen transfer heat directly from one end of the piston to the other.

I have illustrated an embodiment'of my I invention in the accompanyingdrawing, in \which- Figure 1 is a longitudinal section-through, an internal combustion engine; Fig. 2 isa longitudinal section throughthe piston; Fig. 3 is a transverse section on the line A, A', of Fig. 2; Fig. 4 is a transverse section on .the line B. B. of Fig. 2.

Referring to-these drawings, the engine is shown as provided with a cylinder 1, having a cooling jacket 2', and the end of the cylinder is closed bya head 3, in which are arranged the devices for controlling the supply of gas'orother fuel, air and cooling water flowing to and from the water jacket 2. Within the cylinder 1, is a reciprocating piston 4, the movement of which is transof the engine, and the fly-wheel 7. In this engine the combustible mixture is ignited in the chamber between the head 3 and the 5 adjacent end of the piston 4 and the central portion. of that end of the piston is continuou sly heated to a relatively high degree. The other end of the piston, however, is never in direct cont-act with the combustible mixture so that its temperature would be substantially lower than that of the opposite end of .the pistonif the construction heretofore commonly employed were used. .In" the construction shown, however, the piston 4 is made hollow and within .the closed cavity in the piston is a substantial amount of water'or other liquid preferably filling the cavity to the extent indicated at 8, in- Fig. 2. When the piston so construct- 20 ed is reciprocated within thecylinderof the engine, the water flows to and fro within the cavity in the piston. As shown in Fig. 1, the piston is in the dead point at the left end of its reciprocating movement and the whole of the end of the piston which comes in contact with the combustible mixture is covered by the water. When the piston is at the other end of the stroke, the opposite end of the piston and the cylindrical walls adjacent thereto will be covered with water; therefore, during each stroke of the piston, the heat which has been t'alien up by the end of the piston from the explosive gases will be taken up by the water and distributed over the other walls of the piston as a result of which all parts'of the piston will be maintained at a substantially uniform temperature. In order to facilitate the transfer of the heat from the end of the piston which is in contact with the explosive gases, I provide the interior surface of that end of the piston with a. plurality of projections 9, and one or more'similar projections may be provided upon the cylindrical wall of the piston adjacent to that end. These projections enlarge the heat. radiating surface and furthermore they serve to increase the circulation of the water within the closed cavity in the piston. The cylindrical wall of the piston may be provided with ribs 10 which extend either longitudiually or spirally relatively to the axis of the piston. These ribs aid inefiecting the circulation of the water within the pis ton'. After operation of the engine for a substantial period of time, the water within the piston will be heated to -a"relativel'y high temperature, but even then this water within the piston will serve toatt-ain the main object. of the invention which is an even distribution of the heat over the whole of the piston. I have found that the great difference of temperature between different parts of the. piston of an engine of'this character, has always been a source of great danger in engines constructed in the manner heretofore common. With the .con-

struction herein shown, smooth operation of the engine is readily obtained, particularly as to-lubrication of the interior of the cylinder, and the piston may be readily effected due largely to the. fact that the piston is maintained at a substantially uniform "temperature throughout all parts thereof. Moreover, the construction adopted for the piston may be governed largely by princiton as provided with but one cavity, but in some cases, I may provide two or'more such cavities the liquid within the piston asbeing water,

but it isv to be understood that any other liquid may be employed, if desired;

What I claim is:

' 1. In an engineya cylinder,- a piston reciprocating in the cylinder and having a cavity formed therein-which is completely closed, and a liquid in the cavity, which liquid, by its movement in the cavity in the piston, transmits heat from the highly heats ed portions to the 'less heated portions of the piston; substantially as described. I

2. In an engine,*a. cylinder, a piston reciprocating in the cylinder and having a cavity formed therein which is completely closed, a liquidwithin the cavity, and means for causing circulation of the liquid within the cavity as the cylinder isreciprocated;

substantially as described. I I

der, a hollow pis- 4 3. In an engine, a cyhn ton reciprocating therein,a liquidconfined within but not filling the, hollow piston, and

ribs formed on the interior walls of the hol,'

low piston; substantially as described.

In testimony thereof I have signed my name to this specification in the presence of two subscribing witnesses.

- 4 'HUGO 'JUNKERS'. I Witnesses: 3

EMIL WERGIEN,

' HERMANN Tisonnn.

by arranging divisional walls within the piston; also, I have referred to' 

